Screw-on display holder for the OpenBikeSensor

A screwable holder for the display unit of an OpenBikeSensor

OpenBikeSensor is an open source, open data and citizen science project.
See https://www.openbikesensor.org/ (only in German language available).

You can find a translation of the description in the PDF “Instructions_OBS-DisplayUnit_tactileSwitch” of my alternative display unit for the OpenBikeSensor.
 

Sliding on the rail:

The snap-lug is not working as you would expected this due to printing reasons - overhang and force in the plane of layer adhesion. Therefore it's not possible to design the shape as it should be.
You should need a little bit of force to push on the display case (there are no magnets in the holder). The snap-lug will be bent down and add additional force and therefore friction force.
If the case is sliding too lightly, think about scaling the holder in one direction (x or y-direction) to about 102% (or even more if sliding is still too light).

Part list:

• ScrewFix and Counterpart for your preffered diameter of the handlebar.
• 2x Socket head screw ISO4762 (DIN 912) M3x14 (or M3x16 or M3x18), steel or stainless steel, doesn't really matter)
• 2x Hexagon nut ISO 4032 M3 (steel or stainless steel)

Which Files?

Measure the diameter of the handlebar. At the moment there are models for diameter 32 mm and 22 mm available. This should suit for diameters up to 4 mm smaller (4 mm clamping gap).

• Diameter 32 to 28mm “d32mm” in the filename
• Diameter 22 to 18mm “d22mm” in the filename

The length differs, depending on the display case you use:
For the standard case (the one with magnets) take the holder with length 35mm (L35mm).
For my designed Display unit you need either 30mm or 33mm, depending on the size of your LCD/OLED.

 

Printing:

Printing in PETG is advised.

Nozzle 0.4 mm, Layer height of 0.2 mm, 5 wall loops, 4 top and bottom layers, infill 30 % (but nearly nothing needed), infill pattern triangles, no support.

Hint for OrcaSlicer (I don't know how other slicers handle this): Wall printing order In/Out gives better results at the screw holes and the snap-lug because of printing the inside before printing the overhang line.
As mentioned above, if sliding on the dovetail rail is too light, scale a little bit in x- or y-direction (~1-3%, start with lower values).

Mounting of the nut:

The part was designed for pressing in the nut, so it will not fall out while handling. To mount the nut take the counterpart and one M3 screw (easier with a M3x8 like commonly used for assembling the OBS), insert the screw through the hole and fasten (see photos). The nut will be pressed in into the hexagon pocket.

Mount it on a bike:

The holder should also be usable for handlebars with a diameter of around 4mm smaller than the model-diameter (4mm gap).

Other dimensions:

The published holder is designed with a vertical gap between the handlebar and the bottom side of the display case of 4mm and a distance horizontal of 15mm away from the clamp - I think that should suite for most cases.
 

FreeCAD-files:

Parameter table in top case was used, but the bottom case lost this connection when saving a copy or renaming - breaks the link between part and counterpart, I don't know how to fix this at the moment.

Best to copy and rename the files to be able to open the copy and the file to be edited at the same time - even changing dimensions can lead to errors, it seems this ist the topological naming problem. Once you have opened both files, you can see which edges are to be selected for the faulty chamfer and/or radii.

Updates

• Update 11.07.2025:
  • Files tidied up, both Step and Freecad. Both parts (rail and clamp) are in one file. Only two FreeCAD files left, customize the length of the rail in the Parameter table to your requirement.
  • Clearer print description

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